High Point #38A Dark Blue Filter - 1.25"
This #38A Dark Blue Filter by High Point Scientific, 17% transmission is an invaluable aid to lunar and planetary observing. This filter will reduce glare and light scattering, increase contrast through selective filtration, increase definition and resolution, reduce irradiation and lessen eye fatigue. The Dark Blue Filter has a Wratten number of #38A and can help you view the many surface features of Mars. A deep blue filter is useful for observing the Great Red Spot on Jupiter, or to enhance the boundaries between the giant planet's reddish belts and their adjacent bright zones. Use a blue filter to enhance Mercury's surface markings at twilight, when the elusive planet is low on the horizon. With a transmission of 17%, this dark blue filter increases comet tail definition.
All of High Point's colored filters are made of high quality, solid-plane parallel glass that has been anti-reflection coated to prevent glare and ghosting. They have a full 26mm clear aperture and are mounted in a black anodized aluminum cell that is threaded on both sides to fit most 1.25" eyepieces and stack with each other.
Please note that the effectiveness of this filter depends on several factors, including the aperture and focal length of your telescope, the magnification being used, and the seeing conditions at the time. Remember that filters lower the amount of light that reaches your eye. You'll need an aperture of at least 8 inches for dark filters such as the #47 Violet, with only 3% transmission, the #25 Red with just 14% transmission, or the #38A Blue with 17% transmission.
Dimensions & Specifications
Model Number: 38AF1
Filter - Single or Set: Single Filter
Filter Size 31.75 mm (1.25")
Filter Type: Planetary Color
Filter Shape: Round
Mounted or Unmounted: Mounted
Wratten Number or Equivalent: #38A Dark Blue
Filter Warranty: Two Years
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Return & Exchange Policy
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